Bone conduction audifhone



Aug. 7, 1945. H. KOCH v BONE CONDUCTION AUDI PHONE Original Filed Aug.51, 1935 IIIEI I 'IIIII Ill lirrnllu PIC-5.6

INVENTOR:

HENRY KOCH, 1 nd I MY AM ATTORNEYS Relates A 1, 1945 1 UNITED STATESPATENT ori ice sons CONDUCTION anmrnom: Henry Koch, Jamaica, N. Y.,aasignor to Dictagraph Products Company, a corporation of Delaware lnc.,New York, N. Y.,

Original No. 2,144,458, dated January 1'1, 1939, Se-

rial'No. 38,882, August 31, 1935. Application'for reissue January 18,1940, Serial No. 314,564

9Claims. (curs-107) I Thi inventionrelates to ,audiphones and hasparticular reference to audiphone receivers having a vibrating elementadapted to be placed in operative connection with the bone structure ofthe user for transmitting audible,- sounds picked up by a suitablemicrophone to the inner car through the bone structure.

In copending application Serial No. 678,13 filed June 29, 1933, nowPatent No. 2,148,024, there disclosed a bone conducticn receiver whichis characteristic in that the electromagnetic means of the receiver issupported by the tympanum or reed, so that, in response toenergizationby voice currents, the inertia of the electromagnetic ineanscauses it to in direct remain stationary while .the tympanum or reedvibrates relatively thereto. The casing of thereceiver issecuredtmthetympanum or reed'and consequently vibrates over its entiresurface, so that any portion thereof may be supported by a head-band orother holder in operative connection with the bone structure of theuser, such as on the mastoid'eminence, for transmitting its vibrationsther'ethrough.

-This device has proven reasonably satisfactory. but because the surfacearea of the casing-wall which, engages the bone is relatively large, a

considerable amount of power is required to pro-- duce sumciently strongvibrations to enable the r-to hear well. .In this respect the so-calledbutton type of bone conduction receiver, in which a button carried bythe, tympanum or reed engages the bonestructure, has certain advantages,because the area or contact of the button is relatively small and itsvibrations are concentrated and it is not necessary to vibrate theheadband, I

with the result that less poweris required'to operate the.receiver.-However, the button type ofbone receiver as heretofore constructed isnot practicable, because the pressure'which must be applied to theelectromagnetic means inv order to secure firrncontact between thebutton and the bone causes the vibrations of the tympanum or reedjo besuppressed and sometimes closing of the magnetic gap.

In accordance with one form of.the present invention, a boneconduction'receiver is provided in which the advantagesofthe button typereceiver, in so far as concentrated'vibration and reducedpower-consumption are concerned, are combined with the advantages of thereaction or inertia type bone receiver. in so far as practicability andoperating effectiveness are concerned.

.The aforementioned form of the invention has several modifications, oneof which comprises 1m electromagnetic means-supported by its tympanum orreed the face plate of a casing adapted to be supported'by a headband orthe like in position for operative connection with the bone structure ofthe user, and having a button extendin through the face plate andconnected to the electromagnetic means so that the receiver casing, dueto the inertia of the electromagnetic means, vibrates as a unit and atthe same time the button concentrates a portion of the vibrations. Inthis way, the face plate engages a relatively'larse area of 'the boneand the button engages a relatively small area of the bone, and theinstrument combines the advantages of the button and inertia or reactiontype of bone receiver without having the disadvantages of these twotypes of devices. The electromagnetic means I is preferably of thecantilever type with the button located adjacent the fulcrum, to producepowerful button vibrations of small amplitude.

Another modification of the invention comprises a casing supported by aheadband or other holder and having the electromagnetic means securedthereto in such a way that the tympanum or reed vibrates freely thereinwithout producing a reaction sufliclent to materially vibrate thecasing, because the inertia of the reed is relatively low. Secured tothis tympanum or reed is a button projecting through the face plate ofthe casing for operative connectlonwith the bone structure oi'the user,the tympanum or reed being still and substantially unaffected by anypressure whlch'is applied to the button by contact between it and thebone structure of the user. In this form, the so-called button effectpredommates, as compared to the inertia or reaction effect.

In another form or the invention, the electromagnetic means is. securedto the casing, which is supported by the headband, while the contactor,adapted to operatively engage the bone structure of the user, is securedto the tympanum or reed, so that the reaction eiiect'is relatively smallbecause the inertia oi the tympanum or reed is low compared to that ofthe electromag- This form of the invention is, in

netic means, effect. a button type receiver in which'the contactorbuttonmayconstitute a small part of the I face plate area or may have alarge area, such as a large prop rtion or all of the area of the faceplate. In that respect,-the' device is similar in app arance to theinertia reaction type of receiver, but differs in operation therefrom,since ms whole casing- -is not vibrated andhence it is not necessary tovibrate the headband. Resilient means is preferably inter-posed betweenthe easness of the vibration thereof.

It will be seen that with the several forms of this invention-theadvantages of the button and N ing drawing, in which:

fried by two filamentary conductors 2| to ltricaliy connectedby springthe corresponding V ico'rd l1 inserted in openings 32 of the casing IQ.

out of tbe'barmagnet iusted position-by means'oflock nut 24.

whereby contact between the reed and the pole piece is prevented in caseof undue pressure on the face plate, without any reduction ineffectiveinertia reaction types, of bone conduction re ceivers arecombined with the result that a more emcient and more effectiveinstrument is produced. v

For a more complete understanding of the in- :vention reference may behad to the-accompany- Figure 1 illustrates the new vbone conductionreceiver of this invention,-supported on the headband and connected in.a microphone circuit;

Fig. 2 is an enlarged-,longitudinal section through the receiver of Fig.1;

Fig. 3 is an enlarged longitudinal section through a modified form ofthe receiver of Fig. 2; Figs. 4, 5 and 6 are enlarged longitudinalsections through other modifications .ot the invention; Figure 'l is aview in side elevation of a modified type of receiver embodying the,invention;

and

' Referringto Fig. 1, the bone conduction re theinner ear of the user.

Figure 8 is a view in section taken on lines-8 Of P181118 '1. a soceiver A includesa casing ll, of hard rubber, phenolic resin, orthe-like. havinga face plate Y H. with a button the latter, and withopposite surface slots id in which the prongs it or the fork-II of theheadband It, or other hoide'r, are pivotahy inserted. .An electriccord-ill, connectible-with separable I! proiectins'slishtly beyond casesa ing and the vibrating contactor or am plate.

illustrated in Fig; 2 is supported by a headband l8,'or the like, in themanner shown in -Fig; 1, so that the face plate II and the button l2 aresimultaneously in operative contact with the bone structure ofthe user,such as the mastoid eminence. Because the. inertia of the magneticstructure, including the magnet 25, the pole piece 28 and the speechcoil 21, is considerably greater than the inertia oi the reed 22 and itsappurtenant parts, the vibration effected by the electromagnetic meansin response to voice currents, causes this magnetic structure in effectto remain stationary while the reed 22 and the casing {2-, ii vibrate asa unit, thus transmitting their vibrations through the bone structure toThe relative vibrations and the magnetic structure are utilized in thisreceiver by means ot the button ILwhich is carried by the magneticstructure and thus trans.- mits concentrated vibrations; through the.bone v structure-0f the user. The spacing of the button i i2 from thefulcrum of the cantilever magnetic structure carrying it, causes thebutton i2 to-prm duce powerful gvibrations of smell amplitude, I wherebypower-requirements are reduced. fie

cordingly, the receiver illustrated in'l ig. 2 combines theadvanta-Eesof the button and inertia or reaction type receivers, operating in thechap acteristic fashion of each. of them without embodying theirdisadvantages:

The receiver-illustratedin cation of the receiver of Fig. 2- in that thebar magnet SI is supported .by a spring.;strip 86 on the reed 31, whichalsowzarries a stiif cantilever spring 38, with respect to which thebar-magnet electric connectors ii to the electromagnetic means withinthe casing l0, includes two wires ll, connected in the circuit of thebattery 29 and the microphone. 2!. Suitable amplifyin means, not shown.may be provided. The receiver A is adapted'to be placed. with its buttonl2 and face plate ll simultaneously inoperative contact with the bonestructure of the user, such as on the mastoid eminence behind the ear,with a headband 18 supporting the receiver A in that posi- "tion.

As is illustrated in Fig. .2, the tympanuzn or -reed 22 is securedrigidly by screws 23, or the like, to the One end-,il; of this reed 22,is turned upwardly and supports cantilever-iashion .the elongated harmagnet '25 .having'at' its;free' d the pole I piece 2'. the end-01.;which'is spaced from the corresponding surface the reed 22 to term anarrow air gap., The speech coil 21 maybe carby the pole piece in, andits terminals are two corresp ndina contact plates 20 inlaid in theinner surface of face plate II and each elecu and plug a to connector l2-oi the electric Adjil stably threaded in t0 the bar magnet I5 3E andconsequently the air gap is adjustable by means of the stem M and nuts4! interconnecting spring 38 and the bar magnet 85. The advent- 40 taxesof adiustability oithe air gap and the m inner surface of the faceplatefl i by means of screws is a stem 28 having at its free end the button ia: which projects approximatei fval to'srof an inch beyond the surfaceof the face-plate ll, in the manner iliustrated in ex'aagerated form inFigs. 1 and 2,.- The degree ot'proiection oi-the screwing stem-2 2 in orII" may lie-adjusted by 2i and locking it in ad- In operation, the boneconduction receiver 7 button l2 semis-the surface of the fac plate tionof 1s avoidance of fatigue of th vibrating metal-by this springstructure are discussed in greater detail in my 'copending applicationSerial No. 733,739, flied July 5, 1934, which discloses the structure ofmg. 3 just described...

In addition toaiiording a means for adjust-- ment of the air gap and thelike, stem as also carries the button i2- and is adjustable axially,

in the bar magnet to'vary the degree of. projection of the button H,which is locked in adiuswti position by lock nut M. The, operation oithe form illustrated in Fig. 3 is the samehs that described inconnection with the arrangement or Figs. 1 and 2.

in the modification illustrated in Fig. i, the bar-magnet .42 isrigidlysecured to the back of 64. so that the Feed 85, extendsparallelixi-tlie inner sur e-cc of the face plate 45 and is iree tovibrate relatively thereto in response. to-energizatiomof theelectromagnet-m the inertia of 'e'reed 46 is small compared to theinertia of, magnetic structure including the bar magnet-J2, thepole'piece l1 and the voiceeoil 48, together with the casing 43 andfaceplate 4!, the reaction eifect is relatively" the mass of the reedQI, the reaction eflect may-be increased at mall, .a1th0u8h,. byincreasing will.

1 1hreaded through 4: is a stem s cirbetween the reed 22 F isa my byvoice currents. Because r'ying thebutton l2" projectingthrough faceplate forming-a relatively small proporsurface area of the latter; The Idegree Ofwbiection 'oibutton .l2'-' beyond the:

surface of faceplate 4 may be varied by screwcushioning material.eflect, a button. the area of Which is the entire reed 45 by Contact ofbutton l2" with the bone.

'I'hedegree of vibration of the casing 43 may be varied by increasing ordecreasing the mass of the reed l5 and button II". For example, byincreasing their mass the reaction efiect isincreased.

In the form of the invention illustrated in Fig. 5, the bar magnet 5| isrigidly secured by screws 52 to the casing 53, while the reed 54 isrigidly secured by screws 55 to the face plate 55; The face plate 55 andth cooperating surface of casing 53 are spaced apart to permit relativevibration between them and this space is filled by a gasket 51 f softrubber, felt, or other The face plate 55 is, in

area of face plate 55.

Energization of the speech coil 58 in accordance with voice currents,causes reed 54 and face plate 55 to vibrate relatively to theheadbandsupported casing 53, so that its vibrations are transmitted tothe inner ear through the bone structure and little or no vibration isimparted to the head band. The gasket 51 is sufficiently firm to preventsubstantial suppression of the vibration of the reed 54 because of itscontact with the head, and also prevents contact or'freezing between thepole piece 59 and the reed 54. as well as preventing access of dirt intothe casing 53.

Alternatively, the arrangement of-Fig. may

be modified as illustrated in Fig. 6 by inserting the face plate withinthe opening of the casing 6|, so that the plate 60 forms a-large proportion of the area of the corresponding wall of As the reed 62 carryingthe face plate 50 is vibrated by the electromagnetic the receiver.

means, including the bar magnet 53, the pole piece 54 and the speechcoil 55, all carried by the casing 5|, the vibrations of the reed 52 aretransmitted by face plate 50 through the bone structure to the inner earof the user.

Although the reeds 22 and 31 of the forms shown in Figs. 2 and 3 aresupported by the headband I5, inasmuch as the latter is connectedherein, it is to be understood that the invention is not limited therebybut is susceptible to changes in form and detail within its scope.

Iclaim:

, 1. In an audiphone, the combination of electromagnetic means adaptedto respond to varying currents substantially throughout the audiblefrequency range, a casin secured thereto, a relatively stiil vibratorymember connected to the means for vibration thereby, a contactor securedto the member and movable relatively to the casing and forming at leastthe major part of a, wall of the casing, resilient sealing meansinterposed between the adjacent portions of the relatively movablecontactor and the casing, and means supporting the casing with thecontactor in oper-' ative contact with the bone structure of the userfor conducting its vibrations therethrough' to the inner ear.

2. In an audiphone, the combination of a vi-.

bratorymechanism comprising two members, relatively stifl' spring meansconnecting said members permitting a limited relative movement betweenat least portions of both'members, electrical means adapted to respondto varying currents within the audible frequency range secured rectlysecured to the contactor for holding the said last named membersubstantially stationary 4D with the contactor in engagement with thebone and said supporting means, without suppression to the casing in, IIto which the reeds 22 and- 31 are secured, these instruments may besupported by their electromagnetic means, if desired, simply byconnecting the headband t the bar magnet 25 and 35, or the like, throughsuitable openings in the wall ofeasing. II). An example of thisarrangement is illustrated in Figs. 7 and 8, wherein the prongs H of thefork l5 of the headband I6 are shown projecting through openings I3 inthe wall of the casing Ill and pivotally connected to the bar magnet25'.

Similarly, although the electromagnetic means is supported by theheadband in Figs. 4, 5 and 6, inasmuch as the latter is connected to thecasings I3, 53 and BI, these instruments may be by said supporting meanswhen said electrical means is energized. for transmitting the vibrationsof the contactor through the bone structure to the inner ear.

3. In an audiphone, the combination of a vibratory mechanism comprisingtwo members, relatively stiff spring means connecting said memberspermitting a. limited relative movement between at least portions ofboth members, electrical means adapted to respond to varying currentswithin the audible frequency range secured to said'portion of one ofsaid member and operatively opposed :to said portion of the othermemch'ange of support would be to convert the forms receivers and theforms of Figs. 4, 5 and 6 into inertia or reaction type receivers.

ber for relatively vibrating the same, a, casing for said mechanismsecured to one of. said members, a contactor for engagingthe user andforming a wall of said casing, and supporting means directlymechanically connected to said other member for holding the samesubstantially stationary in use for vibration of the contactor andcasing relatively thereto when said electrical means is energized,whereby the contactor transmits its vibrations through the bonestructure to means connecting said members permitting a limited relativemovement between. at least portions of both members, electrical meansadaptedto respond to varying currents within the audible frequency rangeoperatively electrically coupled to said portions of said members forrelatively vibrating the same, a relatively fiat contactor for engagingthe user secured to the member having less inertia and having an area atleast as large as the said portion of said last-named member, andsupporting means directly mechanically cou pled to the member havinggreater inertia for holding the same substantially stationary in use forvibration of the contactor and the low inertia member relatively theretowhen said electrical means is energized, whereby the contactor transmitsits vibrations through the bone structure to the inner ear whenoperatively connected thereto by said supporting means.

5. In an audiphone, the combination of a vibratory mechanism comprisingtwo members having unequal inertias, relatively stiff spring meansconnecting said members permitting a limited relativemovementbetween atleast portions of both members, electrical means adapted to respond tovarying currents within the audible frequency range operativelyelectricallycoupled to said portions of said members ior relativelyvibrating the; same, a relatively flat contactor for engaging the usersecured to the member having less inertia and having an area at least aslarge thecontactor and the reed member relativelyas the said portionofsaid last-named member,

supporting means directly mechanically coupled to the member havinggreater inertia for holding the same substantially stationary in use forvibration of the contactor and the low inertia member relatively theretowhen said electrical means is energized, whereby the contactor transmitsits vibrations through the bone structure to the inner ear whenoperatively connected thereto by said supporting means, and resilientmeans interposed between said contactor and a fixed part of theaudiphone for limiting the movement of the contactor relatively to'saidpart under excessive pressure between them.

6.'In an audiphone, the combination of a vi- 'br'atcry mechanismcomprising a relatively flat reed member and a cooperatingelectromagnetic member including a permanent magnet, rela-- tively stiffspring means connecting said members permitting a limited relativemovement between at least portions oi. both members, a voice coiloperatively associated with said electromagnetic member and adapted torelatively vibrate said portions of said members when energized byvarying currents within the audible frequency range, a relatively flatcontactor for engaging the user secured to said reed member and havingan area substantially coextensive therewith, and a supporting meansdirectly mechanically coupled tcsaid magnet for holding th'e samesubstantially stationary in use for vibration of thereto when said voicecoil means is energized. whereby the contactor transmits its vibrationsthrough the bone structure to the inner car when operatively connectedthereto by said supporting means. I

7 In an audiphone, the combination or a resilient headband,electromagnetic means adapted to respond to varying currents throughoutthe audible frequency range, a. casing enclosing said electromagneticmeans and having a wall forming a contactor, means connecting saidheadband to saidelectromagnetic means for holding said electromagneticmeans substantially stationary, and an armature fixed to said contactorfor vibration by said electromagneticmeans, said armature beingsubstantially stiiier than the headband to prevent the resiliency of theheadband from appreciably flexing and thereby suppressing vibration ofsaid armature.

8. In an audiphone, the combination of a resilient headband,electromagnetic means adapted to respond to varying currents throughoutthe audible frequency range, a. casing enclosing said electromagneticmeans and having a wall movable relatively to the remainder of saidcasing and forming a contactor, means connecting said headband to saidelectromagnetic means for holding said electromagnetic meanssubstantially stationary, and an armature fixed to said contactor' forvibration by said electromagnetic means, said armature beingsubstantially stifier than the headband to prevent the resiliency of theheadband from appreciably flexing and thereby suppressing vibration ofsaid armature.

9. In an audiphone, the combination of a vibrating mechanism comprisingtwo members, relatively stiii spring means connecting said meinbers andpermitting limited relative movement between at least portions of bothmembers, electrical means adapted to respond to varying currents withinthe audible frequency range secured to said portion of one of saidmembers, and operatively opposed to said portion of the other memher forrelatively vibrating the same, a casing for said mechanism secured tosaidother member, said casing having at least one opening thereinadjacent to said orie member, and supportingmeans directly mechanicallycoupled to said one member through said casing opening, whereby saidcasing and said other member are free to vibrate relatively to saidsupporting means and said one member totralismit the vibrations to theinher car when said' casing is operatively connected to the bonestructure of the user by said supporting means.

HENRY KOCH.

